fix: call testService method to store testRunId

[mshanemc]

What does this PR do?

the apex library writes a file when async test runs occur. We left that out when we re-did their commands.

What issues does this PR fix or reference?

forcedotcom/cli#2321
@W-13804720@

[WillieRuemmele]

QA Results

---

✅ : async test runs write output-dir file with test-run-id.txt file

 ➜  sf apex run test --output-dir my-async-res           
Run "sf apex get test -i 7077X00002VOofn -o test-qmnirfu5u0qb@example.com" to retrieve test results
Run with --synchronous or increase --wait timeout to wait for results.
➜  dreamhouse-lwc git:(main) ✗  hub:(DevHub) scratch:(test-qmnirfu5u0qb@example.com)
 ➜  gst 
On branch main
Your branch is up to date with 'origin/main'.

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	my-async-res/

 ➜  more my-async-res/test-run-id.txt 
7077X00002VOofn

✅ : writes on sync runs
✅ : writes correct format to output-dir